ABSTRACT
This chapter aims at uncovering whether electoral contamination, and more specifically, the overlap of electoral arenas, brings about an inflation in the number of parties as compared to what should be expected in a Duvergerian world. Actually, entrance when non-viable would not involve any further consequence if voters concentrated their vote in at most parties, as the Duvergerian theories suggest. A value close to 0 indicates that the number of parties which present candidacies at the district level corresponds to the number of parties which manage to get a seat in the district, in line with what the Duvergerian theories predict. As the value of the dependent variable increases, this imbalance becomes clearer, thus showing evidence in favour of electoral contamination and against the Duvergerian gravity. The value of the dependent variable can be directly interpreted as long as it is an increasing.
